Soft viscoelastic properties of nuclear actin age oocytes due to gravitational creep.
Soft viscoelastic properties of nuclear actin age oocytes due to gravitational creep.
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DOI：
10.1038/srep16607
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发表时间：
2015-11-18
影响因子：
4.6
通讯作者：
Brangwynne CP
中科院分区：
文献类型：
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作者：
Feric M;Broedersz CP;Brangwynne CP
肌动蛋白细胞骨架有助于维持活细胞内的结构组织。在大X中。在卵母细胞中，重力成为主导力，并被核肌动蛋白网络抵消，该网络防止液体样核体立即沉降和聚结。然而，核肌动蛋白的机械性质，以及它们如何促进核体的稳定，仍然是未知的。利用活性微流变学，我们发现核肌动蛋白形成了一个弱的粘弹性网络，模量约为0.1 Pa。由于粘弹性蠕变，受到恒定力的嵌入式探针颗粒表现出连续位移。引力也会引起核体的蠕变位移，导致核体的不对称分布。因此，核肌动蛋白并不能无限期地支持核体的乳液，而只是通过将引力蠕变减慢到约2个月来动力学地稳定它们。这与大卵母细胞的存活时间相似，表明重力蠕变使卵母细胞老化，在长时间尺度上具有致命的后果。
The actin cytoskeleton helps maintain structural organization within living cells. In large X. laevis oocytes, gravity becomes a dominant force and is countered by a nuclear actin network that prevents liquid-like nuclear bodies from immediate sedimentation and coalescence. However, nuclear actin’s mechanical properties, and how they facilitate the stabilization of nuclear bodies, remain unknown. Using active microrheology, we find that nuclear actin forms a weak viscoelastic network, with a modulus of roughly 0.1 Pa. Embedded probe particles subjected to a constant force exhibit continuous displacement, due to viscoelastic creep. Gravitational forces also cause creep displacement of nuclear bodies, resulting in their asymmetric nuclear distribution. Thus, nuclear actin does not indefinitely support the emulsion of nuclear bodies, but only kinetically stabilizes them by slowing down gravitational creep to ~2 months. This is similar to the viability time of large oocytes, suggesting gravitational creep ages oocytes, with fatal consequences on long timescales.